Two tests, radioimmunoassay and ELISA to quantitate serum antibodies against Haemophilus influenzae type b (a common cause of meningitis and pneumonia) have been developed, and antibody results tend to predict protection. We require serum from healthy vaccinated adults to proceed with the evaluation of a nationwide Centers for Disease Control and Prevention (CDCP), standardized protocol. Testing of newly developed pneumococcal vaccines mandates an ability to compare antibody among vaccines produced by different manufacturers and being tested in different populations throughout the world.